Planetary nebulae and H II of the local group of galaxies

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1 The KIAA-Cambridge Joint Workshop on Near-Field Cosmology and Galactic Archeology KIAA, Peking University, Beijing, 2008 Dec. 1 5 Planetary nebulae and H II of the local group of galaxies Liu Xiaowei Department of Astronomy Kavli Institute for Astronomy and Astrophysics Peking University

2 Topics 1. Deep spectroscopy of bright planetary nebulae and H II regions Liu X.-W., Probing the dark secrets of PNe with ORLs, in IAU Symp. #209, Planetary Nebulae: Their Evolution and Role in the Universe, eds. S. Kwok, M. Dopita and R. Sutherland, pp (2003) Liu X.-W., Optical recombination lines as probes of conditions in planetary nebulae, in IAU Symp. #234, Planetary Nebulae in our Galaxy and Beyond, eds. M. J. Barlow and R. H. Mendez, pp (2006) 2. A LAMOST survey of M 31

3 Deep spectroscopy of emission line nebulae Measurements and analyses of lines as faint as 10 6 Hβ in bright nebulae (CNONe ORLs; CELs from rare elements, e.g. fluorine and s- and r-process elements) Mathis & Liu (1999), by comparing the observed [O III] λ 5007/λ 4959 and λ 4931/λ 4959 intensity ratios with theoretical predictions, demonstrate that accurate flux measurements can be achieved over a dynamic range of 10,000 Progress in observational technology has enabled us to address some of the long-standing problems in nebular astrophysics as well as opened up new windows of opportunities. WHT optical spectrum of NGC 7027 (Zhang et al. 2005, A&A, 442, 249) [F IV ] Synthesis of fluorine in AGBs: Liu 1998, MNRAS, 295, 699 Zhang & Liu, 2005, ApJ, 631, L61

4 Te(BJ) (K) The dichotomy of CELs versus ORLs/Continua Te([O III]) (K) Liu et al. 1995, MN, 272, 369 Liu & Danziger 1993, MN, 263, 256 Te(BJ) = 7,200 K Te([O III]) = 10,000 K adf(o++/h+) = 4.7

5 Dichotomy of CELs versus ORLs/Continua The discrepancies between elelctron temperatures and ionic abundances deduced from ORLs/continua and from CELs are found to be ubiquitous amongst PNe and H II regions. The effects are bigger for larger, older PNe. For a given PN, the discrepancy increases towards the nebular center. If the higher ORL abundances are correct, then we don't understand the nebular thermal structure. If the ORL abundances are wrong, we don't even understand the recombinations of hydrogenic ions! solar 86 PNe 1) T e ORLs/Cont. T e CELs i+ i+ X X 2) + ORLs + CELs H H Are the discrepancies caused by temperature fluctuations postulated by Peimbert?

6 Evidence of a new component of cold, metal-rich plasma ORLs NGC 6153 ISO/LWS spectrum NGC 6153 Optical CELs: Eex > 104 K IR CELs: Eex < 103 K Galactic background [O III] 2p2,2s2p3 5 So The nebula contains another presviously unknown component of cold, high-metallcity gas, which is too cool to excite any significant opt/uv CELs and is thus invisible via such lines. In this model, heavy element ORLs arise mainly from the cold (< 1000 K) plasma. S D X/H(CELs) derived from UV, optical or IR lines agree well X/H(ORLs) 10 X/H(CELs) Liu et al. 2000, MN, 312, Tex m 52 m P 500 Nc

7 Photoionization models of NGC 6153 Yuan et al. 2008, in preparation HST/WFPC2 images Hα Chemically homogeneous model [O III] λ5007 Model with H-deficient inclusions ( ) [Ne II ]12.8μm [Ne III ]15.5μm Te= 9007 K NH = 1840 cm 3 ff = M = Msun Te= 815 K N H = 4000 cm 3 ff = M = Msun Normal component H-deficient component H: He: 1000 C: 3.20 H: He: 5000 C: 177 N: 3.80 O: 5.53 Ne: 1.76 N: 150 O: 440 Ne: 177 H-deficient knots are cooled by infrared fine-structure lines: [O III] 52μm, [Ne II] 12.8μm and [Ne III] 16μm The model predicts: Te([O III]) = 8800 K >> Te(H I BJ) = 6080 K >> Te(He I J3421) = 3300 K >> Te(O II ORLs) = 800 K

8 Comparison of plasma diagnostic results adf Te ([O III]) (K) NGC 7009 NGC 6153 M 1-42 Hf Ne (CELs) Te (BJ) (cm 3 ) (K) Ne (BD) Te (He I) (cm 3 ) (K) Te (O II) Ne (O II) (K) (cm 3 ) < O II ORLs arise from ~500 K plasma! And as predicted, in general, T e (O II) < T e (He I) < Te (BJ) < Te ([O III]) (Liu 2003, in IAU Symp. 209; Liu et al. 2006, MN, 368, 1959) NGC M Oxygen in cold component MORL(O) M Oxygen in warm component MCEL(O) M Hf M

9 Comparison of emission line widths of ORLs and NGC 7009 (adf ~ 5) NGC 7009 (adf ~ 5) O II: Black [O III] 4363: Red ESO 1.52m FEROS R = 6 km/s NGC 6153 (adf ~ 10) O II: Black [O III] 4363: Green [O III] 5007: Red Gemini/South ghros R = 2 km/s Liu 2006, in PNe beyond the Milky Way, eds. Walsh et al., p.169 Gemini/South ghros R = 2 km/s Barlow et al. 2006, PNe in our Galaxy and beyond, eds. Barlow M. J. and Mendez R. H., p.367 O II < [O III] < [O II] O II ORLs arise from either colder ionized regions or different spatial regions than those emitting [O III] and [O II] CELs The observed different line widths can be explained by the H-deficient inclusion model, but not by a chemically homogeneous nebula (Zhang, 2008arXiv Z)

10 H-deficient knots in born-again PNe PA=330 J3 J2 J1 J4 Abell 58 Abell 30 Abell 78 H-deficient PNe, only five known: Abell 30, Abell 58, Abell 78, IRAS , IRAS (in GC M22) Iben I., Kaler J. B., Truran J. W., Renzini A., 1983, ApJ, 264, 605

11 He I N II C II O IIO II He II + H He I [Ne III] O II M10 N III Bowen O II He II J3 He II O III Bowen He I [O II] [Ne III] WHT/ISIS spectral analyses of knots J3 and J1 in Abell 30 J3 He I [O III] He I H O II He II He II He II O II M1 He I [Ne IV] [Ar IV] He I N III [O III] Ne II O II [O III] J1 J1 Abell 30: Wesson et al. 2003, MN, 340, 253; Abell 58: Wesson et al. 2008, MN, 383, 1639 ORLs from C, N, O & Ne ions and their relative strengths remarkably similar to those observed in other PNe such as Hf 2-2, M 1-42 and NGC 6153 Properties of the H-deficient knots in Abell 30 and 58 O II ORLs arise from ~ 500 K plasma C/O = (Abell 30 J1 and J3), (Abell 58) Problems with the born-again scenario In Abell 30, H contributes only 1% of the mass of the knots, whereas for the postulated H-deficient inclusions in NGC6153, H contributes 22% by mass (H:He:O = 1:2:0.7). But the difference could be caused by mixing of H-deficient material with normal gas in NGC 6153 It is unclear by what mechanism and by how much the He- and C-rich stellar surface material is ejected? Observations show that the knots are O-rich (C/O < 1), contradictory to the born-again scenario

12 Origins of cold, metal-rich plasmas evaporating planetesimals or nova ejecta? What happen to the orbiting planetary system when the Sun turns a WD and its envelope a PN? In the Orion Nebula, propleds (proto-planetary disks) are being evaporated by the strong UV radiation fields from the θ 1 C Difficult to explain the high ORL abundance of inert gas such as Ne The central H-deficient knot in Abell 58 (V605 Aql) is assumed to have formed in a nova-like outburst which peaked in 1919 (Clayton G. C., et al. 2006, ApJ, 646, 69) The central star of Hf 2-2 is known to be a close binary with a period of 0.4 days (Lutz, et al., 1998, BAAS, 30, 894) The Orion Nebula Hα [O III ] 33".5 33".5 33".5 33".5 Hf 2-2 Abell 58

13 LAMOST surveys site conditions Not many clear nights for the north Galactic polar region! Newberg, Deng et al., 2007, AAS, 211, 1428 Sky background brightens steadly over the years! Zhang W., et al. 2008, in preparation

14 The kinematics and elemental abundance distribution of M 31 a science commissioning program for LAMOST M emission line nebulae (2769 PN candidates) m5007 = 2.5 log F (in cgs units) 1700 GC candidates

15 Are oxygen and neon enriched in PNe and is the current solar Ne/O abundance ratio underestimated? Ne/O versus O/H Planetary nebulae H II regions O/H(PNe) O/H(H II) Ne/O(PNe) Ne/O(H II) Sex A Sex B N 3109 Solar GS98 Solar AGS05 SMC N 6822 LMC MW Wang & Liu 2008, MNRAS (Lett.), in press Ne/H and Ne/O increase with increasing O/H in both PNe and H II regions The enrichment of neon in the ISM lags behind oxygen. The variations of Ne/O versus O/H agree well with the theoretical calculations of Kobayashi et al. (2006) Both oxygen and neon are significantly enriched in LIMS at low metallicity but not at metallicity higher than the SMC. That Ne/O(PNe) ~ Ne/O(H II), regardless of metallicity, suggests a very similar production mechanism of neon and oxygen in LIMS of low initial metallicity and in more massive stars. The solar Ne abundance and Ne/O ratio should be revised upwards by ~ 0.22 dex from the Asplund et al. (2005) values or by ~ 0.14 dex from the Grevesse & Sauval (1998) ones.